With the advent of the computer age, electronic systems have become a staple of modern life, and some may even deem them a necessity. Part and parcel with this spread of technology comes an ever greater drive for more functionality from these electronic systems. A microcosm of this quest for increased functionality is the size and capacity of various semiconductor devices. From the 8 bit microprocessor of the original Apple I, through the 16 bit processors of the original IBM PC AT, to the current day, the processing power of semiconductors has grown while the size of these semiconductors has consistently been reduce. In fact, Moore's law recites that the number of transistors on a given size piece of silicon will double every 18 months.
As semiconductors have evolved into these complex systems utilized in powerful computing architectures, almost universally, the connectivity and power requirements for these semiconductors have been increasing. In fact, the higher the clock frequency of the microprocessor, the greater that microprocessor's power consumption (all other aspects being equal).
Turning briefly to FIGS. 1A, 1B, and 1C, one example of a semiconductor package 100 is depicted. Die 110 containing an integrated circuit, such as a microprocessor, is attached to substrate 120. Ball grid array (BGA) balls 130 serve to couple die 110 to a power source or signal input/output-lines. Typically substrate 120, with which microprocessors or semiconductors are packaged, is made of organic material (such as epoxy resin). Substrate 120 may be fabricated using build-up technology, which enables higher wiring capability by having fine-line build-up layer(s) on both sides of a coarser core substrate. Typically, these layers or planes of substrate 120 are coupled to BGA balls 130 through the use of vias.
These BGA balls 130 may then be coupled to a printed circuit board (PCB) which contains a power supply. In most cases, however, impedance of package 110 is smaller than the impedance of the PCB coupled to package 110. These dissimilar impedances may cause current to flow more easily in the power distribution network of package 110 than in PCB 220. This, in turn, may cause more current to flow through BGA balls 130 proximate to the power supply on the PCB.
Thus, a need exists for a power distribution network which reduces current crowding in the network and which effectuates a more equitable distribution of current.